盐度对新吉富罗非鱼受精卵孵化和仔稚鱼活力的影响

Influence of Salinity on Hatching Rate and Larval Vitality in NEW GIFT Nile Tilapia Oreochromis niloticus

研究了盐度梯度对新吉富罗非鱼(Oreochromis niloticus)受精卵孵化和仔鱼活力的影响。水温(28±0.5)℃下,观察比较了8个梯度的盐度(3‰、6‰、9‰、12‰、15‰、18‰、21‰、24‰)及纯净淡水(盐度为0)条件下,新吉富罗非鱼受精卵的孵化时间、孵化周期、孵化率和畸形率。同时在不同盐度条件下对4批初孵仔鱼进行耐饥饿实验,测定其不投饵存活系数(SAI)值。结果表明,新吉富罗非鱼受精卵在盐度6‰～15‰时,孵化率较高(89.0%～92.7%);盐度低于3‰和高于18‰时,孵化率较低。仔鱼生存适宜盐度3‰～15‰,最适盐度6‰～9‰。新吉富罗非鱼仔鱼在盐度0～3‰及18‰～24‰时,仔鱼的SAI值较低,不适宜仔鱼培育;盐度为6‰～15‰时,仔鱼的活力较高。仔鱼的SAI值与受精卵的孵化率呈正相关关系。

Influences of salinity on hatching rate and larval vitality in NEW GIFT Nile Tilapia （Oreochromis niloticus） were investigated. Eight different levels of salinity were set as follows： 3‰,6‰, 9‰, 12‰, 15‰, 18‰,21‰,24‰ and freshwater at temperature of 28 ± 0.5℃. The hatching time, incubation period, hatching rate and deformity rate of the embryos were observed. Four broods of newly hatched larvae were used to for starvation tests and SAI （survival activity index ） evaluation. The normal embryonic development and high hatching rate （89.0%-92. 7% ） were observed at salinities from 6‰ to 15‰,while low hatching rate occurred at a salinity of both less than 3‰ and more than 18‰. The result show that the suitable salinity for the survival of larval hybrid tilapias ranges from 3‰ to 15‰. Salinity below 2‰ or over 17‰ is not suitable for the larvae. At salinities from 6‰ to 15‰,the SAI values were high. The SAI of larvae was positively related with hatching rate of fertilized eggs.